The present invention relates to apparatus for splitting or separating yieldable materials. More particularly, the present invention relates to apparatus for performing a wedging function on any material having a softer composition than the material from which the wedging apparatus is fabricated. The present invention is particularly useful for splitting logs, lumber products or the like but has other utilities that will be readily apparent from the description herein. For instance, the invention can be used for driving holes into the earth, splitting rocks, and so forth.
The problem of how to split logs and the like lengthwise has been predominantly resolved by the use of angular shaped wedges which are pounded into the log by mauls, sledgehammers or other instruments. The task can be satisfactorily completed by use of such implements but certain hazards and difficulties are inherently encountered. For example, the top of the wedge frequently releases flakes of metal upon impact, the holding of the wedge in place for initial striking necessarily exposes the user to injury especially to the hands and arms, the head of the maul or hammer may glance from the head of the wedge or unexpectedly separate from the handle exposing the user to serious injury, etc. Furthermore, particularly with large hardwood logs, the wedge will enter the log to a point where it can no longer be struck by the maul but is securely held in that position by the log thereby requiring the use of additional wedges or some other procedure for completing the log splitting. Additionally, the wedges and hammers needed for this form of log splitting somehow seem to frequently be in widely sparated locations when they are needed as anyone who has had any experience with log splitting by this procedure can attest.
One prior art solution to the myriad of problems associated with log splitting as mentioned above is through the use of hydraulic powered wedges. This solution is not attractive to the average log splitter since the device is expensive, inconvenient to transport, requires a suitable frame for holding the logs in place, and involves multiple moving parts that are subject to costly repair. Although lever actuated cutter devices such as that shown in U.S. Pat No. 2,526,362 by Johnston may be adapted for transverse cutting of some logs, these type devices are not suitable for lengthwise log splitting especially in view of the awkwardly large log holding frame that would be needed as well as the excessively long cutter elements and lever lengths for adaption to log splitting. Even if so adapted, the Johnston type apparatus would not be convenient for easy transport by an individual user.
So-called captured hammer devices have been suggested in the prior art such as in U.S. Pat. No. 2,474,037 by Cuthrell and U.S. Pat. No. 3,050,095 by Prather. Cuthrell employs a tractor mounted trip-hammer type mechanism wherein the wedge element is positioned upon a reciprocally moveable carriage so that it can be raised by the tractor's winch and released to fall upon the object to be severed. Prather shows an elongated stem of a hexagonal cross-section with a piercing tip on one end and a large diameter weight slidable on the stem between two stops. Neither device is acceptable to the average log splitter since, in the case of Cuthrell, an unacceptably complex mechanism is required whereas for Prather, the elongated stem must be at least approximately as long or longer than the longest log that may be split. Prather further requires acceptance of exposed anvil surfaces at the stops, a hazard somewhat similarly involved in the Cuthrell device. Further, a typical disadvantage of prior art manually operated captured hammer devices, such as the Prather device, the shock generated by the hammer portion on the impact surface is transmitted through the rigid hammer structure and associated rigid handles to the operator's hands and arms. This constant repetition of such shock applied to the person's hands and arms cause discomfort, soreness and premature fatigue that can be quite painful and debilitating to a person after extended use of such devices.
Another prior art attempt to overcome the difficulties of single wedge use is suggested in U.S. Pat. No. 3,865,163 by Root wherein outwardly pivotable jaws are hinged to the wedge element to spread the log sides as the wedge enters the log. However, various mechanical disadvantages render these devices unacceptable such as the difficulty in selecting a universally usable jaw length and reliability problems with long-term usage because of the stress associated with the jaw pivot points.